Few fighters stepped into the ring more often than Maxie Rosenbloom, who fought 299 times in sixteen years. Raised on the Lower East Side of New York, Rosenbloom left school after third grade and later served time in reform school. Reportedly, actor George Raft spotted the young Rosenbloom in a street brawl and advised him to become a boxer. Rosenbloom had an unusual style. He was a weak puncher and often slapped at his opponents with an open hand-earning him the nickname "Slapsie"-but he was a consummate defensive fighter and did whatever was necessary to avoid getting hit. He won the vast majority of his fights, although he only recorded nineteen knockouts in his entire professional career.

Rosenbloom turned pro at the age of nineteen and quickly became ranked as a contender, placing tenth in the 1925 annual rankings by The Ring. In 1927, Rosenbloom faced Jimmy Slattery-who had already beaten him twice-for the vacant NBA light heavyweight title. Slattery again won the decision. Over the next couple of years, Rosenbloom kept up a rigorous schedule, battling 46 times in 1928 and 1929.

In 1930, Rosenbloom again faced Slattery in a title fight. Rosenbloom took the decision in fifteen rounds and won the world light heavyweight championship, as recognized by the New York State Athletic Commission. Most ring experts considered Rosenbloom the best light heavy-weight in the game, and he was acclaimed as the undisputed champion when he defeated Lou Scozza in July of 1932.

Rosenbloom held the title until 1934, when he lost a decision to Bob Olin, although many sports writers at ringside believed Rosenbloom had won. Along the way, Rosenbloom fought John Henry Lewis, winning three of their five matches. Rosenbloom had a reputation of fighting just about anyone who would get in the ring with him. He once asked for a match with Joe Louis. As the story goes, Louis was confident of winning but declined because he feared Rosenbloom would make him look bad.

A lively character, Rosenbloom didn't devote much time to training. Although he stayed away from alcohol, he enjoyed gambling, the company of women, and late night celebrations. Rosenbloom parlayed his colorful reputation into a successful acting and night club career, often portraying a punch-drunk fighter.